The invention relates to a four-stroke internal combustion engine with a crankcase and at least one cylinder arranged in this crankcase and in which a working piston is guided by a crankshaft, with at least one cylinder head that closes the cylinder and whose intake and exhaust ports are managed by at least one intake valve and exhaust valve loaded with a closing spring, wherein these valves can be activated by transmission elements driven by the camshaft, and with a brake control device by which pressure is built up in the exhaust system, in particular, in the exhaust channels, and/or an additional opening of at least one exhaust valve.
Such a class-forming internal combustion engine is generally known. Known are, furthermore, several systems for engine-brake controlling.
One system includes an exhaust-gas choke that is arranged in the exhaust-gas system of the internal combustion engine. Here, the engine must work against the increased pressure in the exhaust-gas system and thus generates braking power.
A different system, disclosed in DE-39 04 497 C1, has a decompression device. In this system, before the end of the compression cycle, the exhaust valve is opened and thus the generated pressure in the combustion chamber is released. Therefore, the energy for the subsequent depressurization cycle is no longer returned to the engine and a braking effect is generated.
It is furthermore known, from EP-0 974 740 A2, to keep open one of the exhaust valves during the braking process, in order to hold it open a small amount, so that continuous decompression with corresponding braking effect is realized.
It has been shown that hydraulic valve clearance compensation elements, also called “HVA” in the present patent application, do not function or do not function satisfactorily in connection with braking devices, because there is the risk, e.g., that the “HVA” makes an undesired adjustment during the braking operation.